Mechanical slot switch



Aug. 31, 1965 F. J. GOEZBELS, JR

MECHANICAL SLOT SWITCH Original Filed March 1. 1963 United States Patent 3,204,242 MECHANICAL SLGT SWITCH Frank .1. Goebels, .112, Los Angeles, (Ialifi, assignor to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Continuation of application Ser. No. 261,964, Mar. 1, 1963. This application Mar. 25, 1965, Ser. No. 445,841

9Clairns. (Cl. 343-768) This application is a continuation of application Serial N0. 261,964 filed March 1, 1963 of the same title.

This invention relates generally to microwave devices and more particularly to an apparatus for mechanically switching on and off the energy radiated by a slot in a waveguide.

Heretofore, slot switching was achieved by employing transmission line switching devices remotely disposed from the slot radiator between it and the signal source. Thus, in a slot array, for example, separate transmission line sections, each having a switching device, were required for each slot in order to obtain the desired switching response of the array. Such a complex corporate feed structure is no longer necessary in a slot array utilizing the present invention. In addition, existing slot arrays may be readily modified in accordance with this invention without detuning the slots and causing a shift in the original resonant frequency.

Prior to the present invention, there has been no teaching on slot switching wherein the switching apparatus itself was disposed adjacent to and within the plane of the slot. Such an .arrangement is not only simple and compact but readily permits modification of existing slot arrays regardless of their group configuration.

In brief, the present invention provides a radiating slot in a waveguide wall and a coaxial transmission line disposed in the wall and electromagnetically coupled to the slot. The coaxial line is terminated at one end with a movable short or plunger with the center conductor of the coaxial line extending from this plunger across the slot and grounded to the waveguide at the slot side wall. By adjusting the position of the plunger relative to the slot, the coaxial transmission line can be made to reflect eith r an open circuit or a short circuit impedance in shunt across the slot; accordingly, the slot may be defined as being on or off, respectively. By now displacing the plunger back and forth one quarter waveguide length, on-olf switching is attained.

The advantage of the present invention may best be realized in the antenna art where slots as radiating elements are frequently used. For example, a single antenna array may comprise different groups of slot radiators located in the common aperture wall of the antenna. By selective switching between different slot groupings, a variety of radiation patterns may be generated. Or, by on-of'f switching of individual :slot radiators, the antenna aperture may be time-modulated to produce a simultaneously scanned antenna array or to provide a reduction in the sidelobe level of an antenna pattern. As another example, slot switching according to the present invention may be used to provide an incremental phase shifting device by locating the slots as couplers on a common wall between two waveguides having different phase velocities. -By switching successive slot radiators on in sequence, an incremental phase shift can be generated in the output port of one of the waveguides upon presenting a signal at the input port of the other waveguide.

Accordingly, it is an object of the present invention to provide a switching apparatus for a slot radiator.

Another object of the invention is to provide a switching apparatus for a slot array wherein selective groups 32%,242 Patented Aug. 31, 1965 of slots may be separately excited to generate desired radiation patterns.

A further object is to provide a switching apparatus for radiating slots that may be mechanically actuated.

In accordince with these and other objects of the invention, there is provided a switching apparatus for microwaves comprising in combination a waveguide having a wall including a radiating slot therein, a coaxial transmission line including a center conductor thereof electromagnetically coupled to the slot, tuning means movably mounted in the coaxial line for varying the impedance thereof, and actuating means for moving the tuning means between predetermined positions within the coaxial line.

The following specifications and the accompanying drawing describe and illustrate preferred embodiments of the present invention, like reference characters being used to designate like parts throughout the drawing, wherein:

FIG. 1 is a perspective view partially in section showing a radiating slot and its associated switching apparatus according to the present invention; and

FIG. 2 is a partial plan view of a slot array comprising two groups of radiating slots and including a switching apparatus in accordance with the invention for each slot.

Referring to FIG. 1, there is shown a portion 10 of a waveguide having a slot 12 disposed in a wall 14. The slot 12 is defined by side walls 16 and 18. A bore 20 extends from the side wall 18 through the wall 14, and a movable short or plunger 26 is disposed in the bore 20. The plunger 26 may be readily displaced within the bore 20 for tuning purposes to be described. A center condoctor 22, electrically connected to the side wall 16 at a point 24, extends across the slot 12 and coaxially through the bore 20. With this arrangement of the center conductor 22 and the plunger 26 partially within the bore 20, an electrical network having coaxial transmis sion line characteristics is produced.

Extending outwardly from the plunger 26 is an arm 28 which may be mechanically linked to an actuator 30 by means of a lever 32. The arm 28 may have a yoke 36 formed at its outer end to receive the lever 32 in force transmitting relationship by means of a pin 34.

The plunger 26 may includes an opening 38 to receive, for example, a coil spring 40 which may be retained in the opening 38 by means of a conventional retaining clip 42. The spring 40 is electrically connected to the plunger 26 at one end and at its other end to the center conductor 22. Thus, the plunger 26 may be moved relative to the slot 12 without bending the conductor 22.

The arm 28 may also be threaded so that clockwise rotation of the plunger 26 will cause it to advance into the bore 21 as necessary for tuning purposes. For example, when the distance between the lowermost portion of the plunger 26, as seen in FIG. 1, and the side wall 18 of the slot 12 is an odd multiple of one quarter waveguide wavelengths, an open circuit impedance exists in shunt across the slot and the displacement currents on the iner surface of the wall 14 will couple to the slot 12 causing it to radiate maximum power. By now superimposing in either direction an additional displacement of one quarter waveguide wavelength to the plunger 26, the coaxial transmission line will reflect a short circuit in shunt across the slot 12 and the displacement currents will couple only to the coaxial transmission line causing the slot 12 to radiate minimum power. By adjusting the limits through which the actuator 30 imparts translatory motion to the plunger 26, the radiation of energy through the slot 12 may be quickly varied between a maximum and a minimum thereby producing virtually on-oif switch ing operation.

selected radiating pattern;

In FIG. 2 a slot array 50 is shown comprising a first group of displacement excited shunt slots 52', 52", 5 and a second group of inclined displaced complex slots 54' and 54". The dotted delineations extending from the slots 52 and 54 are representative of a switching apparatus depicted and described in FIG. 1. Extending from the plungers associated with the slots 52 and 54 are arms 56 and 58 respectively, to which are connected the linkage mechanism 60 and 62, respectively. Actuators 64 and 66, which may be similar to the actuator 30 of FIG. 1, may be independently operated in a prescribed fashion to move the plungers accordingly to determine which slotgroup is to be excited. With such an-arrangement, the slots 52 may be excited to form, for example, a pencil beam pattern during which time the slots 54 are virtually cut oil". Subsequently the slots 54 may be excited to form a different radiation pattern, for example, a cosecant squared pattern during which time the slots 52 are virtually cut oil. Thus, the radiation pattern from a common aperture, as for example in the slot array 50, may be quickly altered by selective operation of the actuators 64 and 66.

It should be pointed out that the slot array configuration of FIG. 2 as shown and described is primarily for illustrative purposes and that other embodiments utilizing the principles of the invention may be readily attained from the teachings here set forth.

Thus, there has been described an apparatus for mechanically switching on and oif the energy radiated from a slot. The switching apparatus is simple and compact and maybe readily installed in new and existing slot arrays.

While only preferred embodiments of the invention have been shown and described, others may be made without departing from the intended scope of the invention, the purpose of the foregoing disclosure being primarily descriptive only and not limiting in any sense.

What is claimed is:

1. Switching apparatus for microwaves within a waveguide having a radiating slot, said apparatus comprising: a section of rectangular waveguide microwave carrier having a wall with a radiating slot therein; a stub-length of a coaxial transmission line physically mounted within the same waveguide wall as the radiating slot and extending transverse to said radiating slot, including a center conductor electromagnetically connected to the wall of sa1d radiating slot; a movable stub coaxial tuning means physically mounted within said waveguide wall and electromagnetically connected to said waveguide wall for varylng the impedance in shunt across said radiating slot; and an electrically isolated actuating means for moving said tuning means between two predetermined positions within said waveguide wall relative to said slot wall, at the first positlon of said tuning means waveguide microwave energy couples to said radiating slot, and at the second position of said tuning means waveguide microwave energy returns to said waveguide.

2. Switching apparatus for microwaves within a waveguide having a plurality of radiating slots, the combinanon comprising: a section of rectangular waveguide microwave carrier having a wall with a plurality of radiating slots therein, said slots being. oriented to produce a prestub-length of coaxial transmission line physically mounted at each respective slot and within the same waveguide wall thickness as the radiating slots and extending perpendicularly transverse to each respective radiating slot, each of said stub-lengths at each respective slot includes a center conductor electromagnetically connected to the wall of each of said radiating slots respectively; a movable stub coaxial tuning means physically mounted at each radiating slot within said waveguide wall and electromagnetically connected to said waveguide wall for varying the impedance in shunt across each radiating slot; and an electrically-isolated actuating means for moving each said tuning means between two predetermined positions within said waveguide wall relative to each respective slot wall, at the first position of each said tuning means the microwave energy couples to said slot, and at the second position of said tuning means the microwave energy returns to the waveguide; and each individual actuating means of each tuning means being interconnected to effectuate any slot to radiate the preselected radiation pattern.

3. Switching apparatus for microwaves, within the radiating slot wall of a waveguide, said apparatus comprising: a rectangular microwave carrying Waveguide having a wall with a radiating slot therein; a stub-length coaxial transmission line physically inserted within the wall thickness of said waveguide radiating slot Wall and transverse to the plane of said radiating slot at one radiating slot side wall thereof, said coaxial line including a center conductor crossing said radiating slot and electrically connected to the other side wall of said slot; a movable tuning means electrically connected to and physically within said Waveguide wall for adjusting the said coaxial line impedance across said radiating slot; and an actuating means external to said waveguide for moving said tuning means between two predetermined positions within said waveguide wall relative to said slot wall, the first position of said tuning means causing microwave energy from the waveguide to radiate from the slot, and the second position of said tuning means causing microwave energy to remain within the waveguide.

4. Switching apparatus for microwaves, within a wave guide having a wall including a radiating slot therein, the combination comprising: a coaxial transmission line having a lumped impedance characteristic physically mounted inside and extending transversely through a rectangular waveguide wall having a radiating slot therein to one side wall of said radiating slot, including a center conductor electromagnetically coupled to and bisecting the length of said slot and terminated at the other slot side wall thereof; a variable lumped impedance tuning means movably mounted on said coaxial line and within said waveguide wall for varying the shunt impedance across said slot; and actuating means for moving said tuning means between two predetermined positions within said waveguide wall and relative to said slot wall, the first of said positions causing said slot to appear as an electrical open circuit, and the second position appearing as an electrical short circuit to impinging microwaves.

5. Switching apparatus for microwaves, within a waveguide having a wall including a plurality of radiating slots therein, said slots being oriented to produce a preselected radiating pattern, the combination comprising: a coaxial transmission line having a lumped impedance characteristic, physically inserted inside a waveguide wall having a plurality of pattern-oriented radiating slots therein, mounted at each of said radiating slots, and extending transversely through said Waveguide wall to one side Wall of said radiating slot respectively, and each respective coax line includes a center conductor electromagnetically coupled to and bisecting the length of said respective slot and terminated at the other slot side Wall of the respective slot; a variable lumped impedance tuning means movably mounted at each respective radiating slot of said respective coaxial line and within said waveguide wall for varying the shunt impedance across said respective slot; and individual actuating means for each respective tuning means for moving said tuning means between two predetermined positions within said waveguide wall and relative to each respective slot side wall, the first said predetermined position causing said slot to appear as an electrical open circuit, and the second said predetermined position causing said slot to appear as an electrical short circuit to impinging microwaves at the respective slot; and each individual actuating means of each respective tuning means being linked together to effectuate any desired slot to radiate the preselected radiation pattern.

6. Switching apparatus for microwaves, within a waveguide having a wall including a radiating slot therein, the combination comprising: a less-than-waveguide-wavelength length of coaxial transmission line positioned Within the wall of a microwave carrying waveguide having a radiating slot and said coax line extending transversely to one side wall of said slot, including a center coax conductor electromagnetically coupled to said slot and electrically terminated at the other side wall thereof; and tunable movable plunger, mounted within said waveguide wall and on said center conductor at a first position to provide a low resistance path between said conductor and said slot wall for said Waveguide microwaves; and actuating means coupled to said tuning means for moving said plunger a quarter waveguide wavelength to a second position relative to said slot wall and on said coaxial line to provide a high resistance path between said waveguide and said slot for microwaves.

7. The combination according to claim 6 wherein the outer conductor of said coaxial line comprises said waveguide wall, the inner cylindrical surface of said outer conuctor being formed by an opening extending coaxially through said wall along said center conductor.

8. Switching apparatus for microwaves within a waveguide, the combination comprising: a waveguide microwave transmission line having a wall including a radiating slot therein and a cylindrical opening passing through a portion of said waveguide wall and terminating at a side wall of said radiating slot; a plunger of conductive material movably carried and physically within said cylindrical opening and in electrical contact with said opening; a wire conductor centrally disposed in said opening and connected to said plunger to the other side wall of said radiating slot; an actuating means connected to said plunger for moving same from a first predetermined position to a second predetermined position for altering the slot radiation respectively from a maximum to a minimum.

9. A switching apparatus for microwaves, the combination comprising: a waveguide transmission line having a surface wall including a radiating slot therein; a stub-length coaxial transmission line having lumped impedance characteristic and extending from a side wall of said slot and transversely thereto in the plane thereof and including an inner conductor crossing said slot and coupled to the other side wall thereof; tuning means movably mounted in said coaxial line and coupled to said inner conductor at one end thereof, for providing an electrical path of predetermined impedance in shunt with said slot for said microwaves, the other end of said conductor being coupled to the other side wall of said slot at the center thereof; and driving means connected to said tuning means for displacing same a predetermined distance relative to said slot to change said impedance and vary the radiation from said slot.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner. 

1. SWITCHING APPARATUS FOR MICROWAVES WITHIN A WAVEGUIDE HAVING A RADIATING SLOT, SAID APPARATUS COMPRISING: A SECTION OF RECTANGULAR WAVEGUIDE MICROWAVE CARRIER HAVING A WALL WITH A RADIATING SLOT THEREIN; A STUB-LENGTH OF A COAXIAL TRANSMISSION LINE PHYSICALLY MOUNTED WITHIN THE SAME WAVEGUIDE WALL AS THE RADIATING SLOT AND EXTENDING TRANSVERSE TO SAID RADIATING SLOT, INCLUDING A CENTER CONDUCTOR ELECTROMAGNETICALLY CONNECTED TO THE WALL OF SAID RADIATING SLOT; A MOVABLE STUB COAXIAL TUNING MEANS PHYSICALLY MOUNTED WITHIN SAID WAVEGUIDE WALL OF VARYTROMAGNETICALLY CONNECTED TO SAID WAVEGUIDE WALL FOR VARYING THE IMPEDANCE IN SHANT ACROSS SAID RADIATING SLOT; AND AN ELECTRICALLY ISOLATED ACTUATING MEANS FOR MOVING SAID TUNING MEANS BETWEEN TWO PREDETERMINED POSITIONS WITHIN SAID WAVEGUIDE WALL RELATIVE TO SAID SLOT WALL, AT THE FIRST POSITION OF SAID TUNING MEANS WAVEGUIDE MICROWAVE ENERGY COUPLES TO SAID RADIATING SLOT, AND AT THE SECOND POSITION OF SAID TUNING MEANS WAVEGUIDE MICROWAVE ENERGY RETURNS TO SAID WAVEGUIDE. 